17例听神经瘤MRI,CT及病理对照分析的初步报道

通过CT及手术病理对照,回顾分析了17例听神经瘤的MRI 表现。采用0.35TMT/S 超导成像系统常规行冠状面T_1加权及横断面T_1、T_2加权成像,层厚5mm 或10mm。CT 用薄层后颅窝扫描并分别以软组织窗及骨窗进行观察。将肿瘤按大小分组,发现大于2cm 的肿瘤即可产生囊变或出血,并压迫脑干或四脑室甚至引起梗阻性脑积水。MRI 除可发现位于内听道内的微小肿瘤外,对肿瘤囊变、出血,脑干、四脑室受压肿,瘤供血血管,肿瘤包膜及粘连情况的显示均优于CT,在骨破坏及梗阻性脑积水的显示方面与CT 相仿。     

听神经瘤CT和MRI诊断的对比研究

目的：对比研究MRI与CT对听神经瘤的诊断价值。材料和方法：就50例手术病理证实听神经瘤患者的术前MRI及CT检查资料，对比观察肿瘤结构(囊变，出血，钙化，肿瘤血管、包膜…)及周围解剖改变（内听道扩大，三叉神经受压、脑干受压移位，四脑室变形…)在两法中的不同显示率及比较两法对病灶定位和定性诊断的不同准确率．结果：CT对听神经瘤诊断的敏感性(检出率)为88%，定位、定性诊断准确率均为68%．MRI则分别为96%．94%、94%．在定位和定性诊断中，MRI较CT为好。对病变周围结构改变的观察以及微小听神经瘤的显示，MRI优点更为明显．结论：分析了MRI和CT漏、误诊的原因后，认为MRI应作为听神经瘤的首选检查方法．     

听神经瘤的MRI征象分析

目的 探讨MRI在听神经瘤诊断中的价值.方法 51例经手术及病理证实的听神经瘤均行MR平扫及Gd - DTPA 增强扫描.分析其MR表现.结果 51例听神经瘤发生于桥小脑角区者43例,内听道内8例,均为单侧发病.肿瘤呈囊实性者31例,实性13例,囊性7例.增强扫描51例肿瘤均有明显强化.结论 MRI对听神经瘤特别是微小听神经瘤的诊断具有重要价值.     

听神经瘤的MRI诊断

分析手术和病理证实的７６例７８个听神经瘤的ＭＲＩ表现，其中２例为内听道内微小听神经瘤，１１例作静脉注射Ｇｄ－ＤＴＰＡ后ＭＲ成像。下列特征有助于听神经瘤诊断：（１）肿瘤以第Ⅶ、Ⅷ神经束为中心生长，病侧Ⅶ、Ⅷ神经束明显增粗，与桥小脑角肿瘤多无明确分界。（２）Ｔ＿２加权图像肿瘤呈低信号或低等混合信号，Ｔ＿２加权图像呈高信号或高等混合信号。（３）注射Ｇｄ－ＤＴＰＡ后肿瘤实质多呈不均匀强化，囊变区无强化。（４）绝大多数肿瘤患侧内听道前后径增大，深径缩短。静脉注射Ｇｄ－ＤＴＰＡ对诊断微小听神经启往往甚为有效。     

椎管内神经源性肿瘤的MRI分析

目的:提高MRI对椎管内神经源性肿瘤定性和定位诊断的准确率。材料与方法:神经源性肿瘤27例(男13例,女14例;年龄7-68岁),经病理证实其中神经鞘瘤18例,神经纤维瘤9例,所有病例最初均经采用快速SE T_1加权和T_2加权序列行MR成像,其中5例还附加作了增强扫描。结果:神经鞘瘤和神经纤维瘤在T_1加权像上未见特征性表现,但在T_2加权像上多数表现为有短T_2低信号的包膜内有长T_2信号或混杂信号,长T_2信号强度与脑脊液者相似。同时,还通过MRI找出了椎管内神经源性肿瘤的分布、位置、形态特征等。结论:神经鞘瘤和神经纤维瘤都有赖以增强的MRI可证实的恒定的增强与形态特征,因此MRI,尤其是增强的MRI可用于判定神经源性肿瘤的性质与位置。     

听神经鞘瘤的MRI：信号与病理对照研究

本文对22例听神经鞘瘤的MRI 信号及病理所见进行了对比研究。在SE-T_1WI 序列中,肿瘤信号较低与瘤体富含的Antoni B 型结构、囊变及坏死有关;而信号较高(=灰质)则与瘤体内致密排列的Antoni A 型结构及黄色瘤样变有关。在T_2WI(SE-T_2WI 或R-T_2WI)序列中,肿瘤呈脑脊液样强信号,不仅与瘤体内所含的囊性变有关,还与:(1)Antoni B 型结构;(2)微小坏死灶;(3)动脉瘤样血管扩张及动静脉畸形样结构;(4)黄色瘤样变灶等结构有关。肿瘤信号相对较弱(稍高于灰质)与瘤体中含有丰富的Antoni A 型结构而其他成份相对少或无有关。     

脊髓肿瘤X线诊断进展

作者使用两种程序作脊髓肿瘤的MRI检查。自旋回波T_1加权法,回波时间30～50msec,重复时间400～800msec;自旋回波T_2加权法,回波时间为200msec,重复时间为2000～3000msec,为了有更好的分辨率,还使用脊髓表面线圈,共分析了40例脊髓肿瘤,包括室管膜瘤,星形细胞瘤,血管内皮瘤,脂肪瘤和表皮样肿瘤。用自旋回波T_1加权法,脊髓肿瘤显示清晰,肿瘤常伴有囊性变,图像上为低信号区,肿瘤组织的信号较正常脊髓组织的信号弱;自旋回波T_2加权成像上,肿瘤组织的T_2延长,正常脊髓显示为黑色,被强信号的脑脊液围绕。静脉注射钆DTPA有助于脊髓肿瘤的诊断,在T_2加权成象中,由于肿瘤组织摄取造影剂,肿瘤的边缘显示清晰,正常脊髓与肿瘤组织形成明显对比,如肿瘤内有囊性变,增强后显示更清晰。注射造影剂后,室管膜瘤迅速被增强,密度高而均匀,而星     

听神经瘤的MRI表现与特征的再研究

目的：研究听神经瘤的ＭＲＩ表现与特征。方法：收集手术和病理证实的１３５例、１３８个听神经瘤的ＭＲＩ，其中微小听神经瘤为１０例，行Ｇｄ－ＤＴＰＡ增强扫描为４２例。结果：听神经瘤的ＭＲＩ的表现主要为：（１）肿瘤以内听道为中心生长，病侧第Ⅶ、Ⅷ神经束较对侧增粗，与肿瘤主体多无明确分界，增强后可见两者相连，颇为特征；（２）肿瘤在Ｔ１加权图像上呈低信号，略低信号或低等混合信号，Ｔ２加权呈高信号或高等混合信号；（３）注射Ｇｄ－ＤＴ－ＰＡ后肿瘤呈均匀，不均匀或环状强化；（４）肿瘤边界清晰，边缘光整；（５）绝大多数肿瘤患侧内听道前后径扩大，深径缩短；（６）微小听神经瘤的ＭＲＩ表现为第Ⅶ、Ⅷ神经束正常或局部结节状增粗，造影后呈结节状或点状增强。结论：ＭＲＩ是检查听神经瘤的有效方法，Ｇｄ－ＤＴＰＡ对微小听神经瘤的诊断很有价值。     

垂体瘤的MRI诊断：48例分析

木文回顾分析了经手术证实的48例垂体瘤的MRI 表现,巨腺瘤28例,微腺瘤20例。应用0.35T 超导成像系统分别行冠状面T_1、T_2加权及矢状面T_1加权成像。MRI 诊断46例与手术相符。96%(27/28)的巨腺瘤在T_1WI 上为中、低信号,T_2WI 上89%(25/28)呈不同程度的升高,瘤内囊变或出血均可定性,视交叉、下丘脑及海绵窦等周围结构的受累可准确显示。微腺瘤之信号变化较大,T_1WI 亦以中低信号为主,T_2WI 可升高也可保持为等信号,结合形态学改变诊断多可确立。作者认为MRI 可弥补CT 的不足,是诊断垂体瘤的理想工具。     

Gd-DTPA对脑和脊髓病灶的增强效果

作者对20例脑脊髓局限性病灶患者(男6例,女14例)行Gd-DTPA检查。首先用T_1加权法(SE法:TR=300或500ms,TE=30或40ms)和T_2加权法(SE法:TR=2000ms,TE=60或80 ms)摄影。继之从肘或足背静缓慢注入Gd-DTPA0.1mmol/kg,约30～40分钟后,行与给药前同样的T_1加权摄影,最后与给Gd-DTPA前的T_2加权像对比。作者见到,①5例均有水肿,T_2加权像描出强信号区,Gd-DTPA在肿瘤部分描出明显强信号区。②3例听神经鞘瘤,T_2加权摄影描出均一的强信号区。而Gd-DTPA增强法均示增强,2例听神经瘤,肿瘤内部分不增强,手术证实为囊肿。③1例肺癌转移,T_2加权见转移灶与周围     

Comparison between air CT and MRI in the detection of small acoustic neurinomas

Air CT proved useful in yielding images of acoustic tumors as an air filling defect in 11 (24%) of 46 patients. Six of the 11 tumors were small ones of less than 1 cm in diameter. Air CT was also able to exclude an intracanalicular tumor in 29 patients (63%). MRI was performed for comparison in eight patients (nine tumors) already diagnosed by air CT as having an acoustic tumor. MRI detected eight (89%) of nine tumors. A false negative result on MRI was obtained only in one intracanalicular tumor (4.3 mm in size). This was considered to be attributable to limitations of spatial resolution including the wide slice thickness. A protocol for radiological investigation and management of patients whose clinical symptoms and/or audiovestibular examination are highly indicative of acoustic tumor is proposed and discussed.     

桥小脑角区肿瘤的磁共振成像诊断

目的：探讨桥小脑角区肿瘤的磁共振成像（MRI）的影像学表现及鉴别诊断,以提高其诊断水平。方法总结分析经影像学及手术病理证实的桥小脑角区肿瘤共33例。其中听神经瘤14例,三叉神经瘤8例,脑膜瘤2例,胆脂瘤3例,蛛网膜囊肿4例,恶性肉芽肿1例,颈静脉球瘤1例。所有患者均行MRI平扫及增强扫描,部分病例结合CT扫描。总结分析肿瘤的形态、大小、生长方式、信号特征及强化方式。结果桥小脑角区的肿瘤以听神经瘤占首位,其次为三叉神经瘤、胆脂瘤、蛛网膜囊肿、脑膜瘤。还有一些少见的肿瘤,诸如恶性肉芽肿、颈静脉球瘤等。结论桥小脑角区肿瘤MRI表现各具有不同特性,了解这些特征有助于诊断及鉴别诊断,为临床治疗及手术提供依据。     

Acoustic neuromas: evaluation by magnetic resonance imaging

Proton magnetic resonance imaging (MRI) examinations were performed in six patients with seven acoustic neuromas, and the results were compared with conventional tomography of the internal auditory canals, contrast-enhanced computed tomography (CT), and air CT cisternography. All tumors were identified with MRI. The three largest tumors (greater than 1 cm diameter) looked similar to the tumors seen on CT scans, although the extent of the tumor was better seen with MRI in two cases. The four small (less than or equal to 1 cm diameter) cerebellopontine angle and intracanalicular tumors were well seen with MRI, with appearances corresponding to those seen with air CT cisternography. No side effects were encountered with the MRI examinations. MRI is an accurate, noninvasive alternative to contrast-enhanced CT and air CT cisternography in the diagnosis of acoustic neuromas.     

The value of T2(*)-weighted MR images for the diagnosis of acoustic neuromas

The aim of this study was to evaluate high resolution T2(*)-weighted MRI—in our case a 3D CISS sequence—for the diagnosis of acoustic neuromas. Especially to be clarified was if high-resolution T2-weighted sequences can substitute T1-weighted contrast-enhanced sequences, and in which circumstances they can give important additional information when compared with contrast-enhanced T1-weighted sequences. Methods and patients: The MR examinations were performed using a 1.5-Tesla unit with a circularly polarized head coil. All 20 patients (11 females, nine males, aged from 12 to 80 years) with acoustic neuromas underwent preoperative MRI with T2*-weighted 3D CISS (slice thickness, 0.7 mm; acquisition time, 8 min) and pre- and postcontrast T1-weighted 3D MP-RAGE (slice thickness, 0.9 mm; acquisition time, 8 min) sequences. The detectability of acoustic neuromas was evaluated following the consensus of three radiologists using a 3D work station (parameters: tumor presence, extent, nerve attribution). Results: All tumors were detected by both contrast-enhanced 3D MP-RAGE and 3D CISS and the diameters of the lesions were equally well measured. 3D CISS was the best sequence for the attribution of a lesion to a certain nerve. Labyrinthine involvement could be better detected using 3D CISS than contrast-enhanced 3D MP-RAGE. Conclusion: High-resolution T2(*)-weighted MRI is a very sensitive method for tumor screening which can also detect even small meatal and labyrinthine neuromas. In the case of abnormal findings (other pathology or variations, e.g. vascular loops); however, contrast-enhanced T1-weighted MRI is necessary in order to confirm the presence of a tumor with typical enhancement.     

MRI screening for acoustic neuroma without gadolinium: value of 3DFT-CISS sequence

To evaluate the efficacy of a gradient-echo sequence (3DFT-CISS) in the diagnosis of acoustic neuromas, two independent observers twice reviewed the images of the temporal bones of 83 patients. Contrast-enhanced T1-weighted spin echo images were used as the reference, showing 18 acoustic neuromas, including 5 purely intracanalicular and one intralabyrinthine tumours. High sensitivity (89-94 %), specificity (94–97 %) and accuracy (94–95 %) were found. Intraobserver (kappa 0.93–1) and interobserver (kappa 0.83–0.84) reproducibility were very good. The smallest intracanalicular tumour was overlooked twice by both observers; the intralabyrinthine tumour once by one observer. All tumours were detected with a less stringent decision criterion, at the expense of lower specificity. Received: 2 September 1996 Accepted: 19 November 1996     

颅内表皮样囊肿的MRI诊断

目的;分析颅内表皮样囊肿的ＭＲＩ表现。方法：收集经手术病理证实的颅内表内表皮样囊肿１４例,重点分析肿瘤的好发年龄,部位、ＭＲＩ信号特点及增强情况。结果：在本组病例中,年龄最小１６岁,最大４５岁,平均年龄２８岁,Ｔ１加权像呈低信号（９例）,低,等混杂信号（３例）、高信号（２例）、肿瘤在Ｔ２加权像上均呈高信号,７例行增强均无强化。结论：颅内表皮囊肿具有特征性ＭＲＩ表现。     

Baseline and follow-up MRI of the internal auditory canal after suboccipital resection of acoustic schwannoma: appearances and clinical correlations

Prospective baseline MRI was obtained on 31 patients who had total removal of acoustic schwannoma 6 months to 9 years previously. Follow-up MRI was performed after 1–2 years on patients with questionable abnormalities. We found four patterns (1) internal auditory canals (IAC) with nonenhancing soft-tissue strands, possibly scars or distorted residual nerves (8); (2) IAC with marginal enhancement-reactive dura mater (16); (3) IAC with contrast-enhancing globular tissues suggesting residual or recurrent tumour (5); (4) high-signal intensity in the IAC before contrast medium administration, probably related to graft with fat/fascia/muscle (2). Prospective 1-to 2-year follow-up studies were available in 8, 5, and 1 patients in groups 2, 3, and 4 respectively. In group 2, dural enhancement remained unchanged in 5 patients and decreased in 3. In group 3 follow-up showed 1 tumor recurrence (surgically confirmed) and 4 stable abnormalities. In group 4, follow-up in 1 of the 2 patients was stable. In groups 1 and 2, the MRI features correlate well with complete tumor removal. Whether follow-up in these groups is indicated needs to be determined. In group 3 residual or recurrent tumor cannot be excluded. In group 4, grafts may prevent adequate visualization of the IAC.     

MRI screening for acoustic neuroma: a comparison of fast spin echo and contrast enhanced imaging in 1233 patients

Gadolinium enhanced MRI is the gold standard investigation for the detection of acoustic neuroma. Non-contrast MRI sequences have been suggested as an alternative for screening examinations. In order to determine the utility of fast spin echo imaging, both gadolinium enhanced T1 weighted images and fast spin echo T2 weighted images were acquired in 1233 consecutive patients referred for exclusion of acoustic neuroma. Two radiologists independently recorded their findings. Fast spin echo T2 weighted images were evaluated with respect to the visibility of nerves within the internal auditory canals and allocated a confidence score for the presence or absence of acoustic neuroma. 33 acoustic neuromas were identified. Only 56% were confidently identified on fast spin echo T2 weighted images alone; gadolinium enhanced T1 weighted images were required to confirm the diagnosis in 44% of the cases, including 9 of the 10 intracanalicular tumours. However, when identification of two normal intracanalicular nerves is employed as the criterion of normality, the single fast spin echo T2 weighted sequence excluded acoustic neuroma in 59% of this screened population. It is concluded that an imaging strategy intended to identify small intracanalicular acoustic neuromas cannot rely on fast spin echo T2 weighted imaging alone. Gadolinium enhanced T1 weighted imaging could be restricted to patients where fast spin echo images do not exclude acoustic neuroma but this strategy requires continuous supervision by an experienced radiologist. In most practices the screening examination should continue to include a gadolinium enhanced sequence in order to optimize the detection of small acoustic neuromas.     

0.5 T MRI of small renal masses: value of T2-weighted and Gd-DOTA-enhanced images

We compared the value of T2-weighted and Gd-DOTA-enhanced T1-weighted images for the detection and characterisation of 33 small renal masses (14 clear cell carcinomas, 6 angiomyolipomas, 3 angiomyomas, 4 adenomas, 3 papillary carcinomas, 3 oncocytomas, 1 haemorrhagic cyst). Dynamic enhanced MRI was performed to study the tumoral vascular supply (19 cases). MRI depicted all the masses more than 1 cm in diameter, but missed all the lesions less than 1 cm (4 false-negative). The results of T2-weighted images and Gd-DOTA-enhanced images were similar as regards detection; however, Gd-DOTA-enhanced images depicted more clearly the tumours smaller than 2 cm (11 cases). MRI enabled the characterisation of only 3 masses (2 angiomyolipomas, 1 haemorrhagic cyst). New MRI features are described for oncocytomas (low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, early and marked enhancement on dynamic enhanced MRI). Dynamic enhanced MRI did not contribute to the differentiation of benign from malignant tumours. Correspondence to: O. Hélénon     

MR cisternography of the cerebello-pontine angle and internal auditory canal in diagnosis of intracanalicular acoustic neuroma

Summary One hundred and fifteen patients, suffering from sensorineural hearing loss were tested with a 1.5 T superconducting magnet. The authors describe utility of both T1-weighted multiple slice and T2-weighted multiple echo images for the evaluation of cerebello-pontine angle, internal auditory canal and their neurovascular content. In seventy-three cases MR cisternography was normal. The remaining forty-two cases were subdivided into twenty extracanalicular masses, eleven small intra-extracanalicular and nine purely intracanalicular lesions. All the lesions were histologically proven acoustic neuromas, except one intracanalicular mass which was a meningioma. Examination was inconclusive only in two cases and decision was then made to follow the clinical course. Advantages of MR cisternography over CT and air CT cisternography, such as absence of ionizing radiation and contrast material, easy multiplanar evaluation of the region of interest and the possibility to delineate both the cisternal and canalar extremities of the tumor mass are pointed out.